摘要
通过真空感应炉试验,研究不同Mg含量处理所获得的不同MgO-Al2O3-SiO2复合夹杂物对凝固组织的影响。试验结果表明,随着钢中Mg含量的增加,铸锭等轴晶率呈现先升高后下降的趋势,而等轴晶尺寸和柱状晶宽度呈现先降低后升高趋势,存在一个最佳的Mg的质量分数范围（5~13）×10-6,铸锭的等轴晶率在70%以上。夹杂物观测并结合热力学计算发现,随着钢中Mg含量的增加,MgO-Al2O3-SiO2复合夹杂物外层逐步析出MgO·Al2O3相;然而,Mg的质量分数高于13×10-6时,夹杂物外层开始析出2MgO·SiO2相。晶面错配度计算表明,MgO·Al2O3与δ-Fe的错配度为1.2%,2MgO·SiO2与δ-Fe的错配度为13%。可以判断,MgO·Al2O3相可促进等轴晶形成,抑制晶粒长大,2MgO·SiO2相则起不到促进形核作用。从而解释了铸锭等轴晶率、晶粒尺寸随Mg含量的变化规律。
The composition of MgO-Al2O3-SiO2 complex inclusion,which formed by adding different quantity of Ni-Mg alloy to steel in MgO crucible induction melting furnace,had a huge effect on the solidification structure of 430 stainless steel.The experimental results show that with the increase of the content of magnesium in steel ingot,the ECR（equiaxed crystal ratio）can be increased at first and decreased subsequently,while the equiaxed crystal size and the width of the columnar should be first decreased then increased,and there exist an optimal range of magnesium content,（5-13）×10-6,in which the equiaxial crystal ingot is more than 70%.By connecting inclusion observation with thermodynamic calculation,when Mg content is less than 13×10-6,with the increase of[Mg],there will precipitate more MgO·Al2O3 phase around MgO-Al2O3-SiO2 complex inclusions;besides,when[Mg]is more than 13×10-6,there is 2 MgO·SiO2 phase around the inclusions.The planar disregistry calculation shows that the planar disregistry between the MgO·Al2O3 and δ-Fe is 1.2%,while the 2MgO·SiO2vsδ-Fe is 13%.It can be concluded that the MgO·Al2O3 around the MgO-Al2O3-SiO2 complex inclusion could promote the formation of equiaxed grains and refine the solidification structure of 430 stainless steel while the 2MgO·SiO2are unable to promote the nucleation,explaining the trend of the ECR and grain size of the ingot along with Mg content.
出处
《钢铁研究学报》
CAS
CSCD
北大核心
2014年第6期61-66,共6页
Journal of Iron and Steel Research
关键词
430不锈钢
等轴晶率
凝固组织
夹杂物
430 stainless steel
equiaxed crystal ratio
solidification structure
inclusion
